How is it that people as a rule have such a dislike for frogs? Many people, even those who live in the country, credit them with the power of spitting poison, and even those who do not share this belief, regard them as creatures to be shunned. Perhaps this short outline of the life-history of these poor creatures, so unjustly 'sent to Coventry,' may gain for them at least a favourable hearing. Frogs make most charming pets, and I am never without a few on my study table. From their lives these facts are taken.

Let us begin from the very beginning—the hatching out of the eggs. Frogs' eggs and birds' eggs are really not so unlike as they seem at first sight, for though the frog's eggs have no shell, yet, just as in the bird's egg, there are two essential parts to be distinguished—the formative material out of which the young frog grows and the yolk on which the growing animal feeds. By the untrained eye nothing more can be seen in the frog's egg than a small black ball enclosed within a clear jelly-like substance. At the time the egg is laid this outer jelly is hardly noticeable, but it soon swells up, and thus forms a soft, elastic covering to the growing frog, effectually protecting it from injury. This black ball, by the way, answers to the yellow yolk of the hen's egg: it differs from the yellow yolk in that it is colourless internally, and black externally. The black outside coat apparently serves to attract the heat of the sun, and thereby to bring about the hatching process, which the hen does by the warmth of her own body.

These eggs are furthermore remarkable in that they are laid, not one by one, as a hen lays, but in thousands, and in water, forming an enormous speckled mass. Take a portion of such a mass and watch it. Day by day you will see the black spot gradually assume a distinct shape (fig. 1, A): a little later a head and tail can be made out.

In a few hours more little black buds grow out on each side of the head, and these soon become branched. They are the future gills. At this time you will notice slight movements within this glassy cradle; and soon after this the young frog, or tadpole, as we must call him now, escapes; that is to say, as soon as he leaves his cradle he becomes a tadpole. At first he does nothing but hang on to bits of weed, or the broken remains of the covering of the egg, by a sticky substance formed by a special pair of suckers placed just behind the mouth, as shown in our illustration (fig. 2).

Soon signs of life become apparent in the shape of a slow curving of the body from side to side. In a very short time, however, these movements increase so rapidly that the tail can hardly be seen, and at last, in one of these violent wriggles he finds himself actually swimming! During all this time he has swallowed no food, but has lived on the remains of the egg within him; swallowing, indeed, has been out of the question, for as yet his mouth is sealed! But now, at last, the little jaws are unlocked, and he begins to eat ravenously, at first delicate green weed, and later, flesh, when it is to be had. I give my tadpoles small pieces of beef, but in the ditches where they swarm, animal matter is to be had in plenty as a rule.

The mouth at this time is a very different structure from that which is found in the adult frog: it is fringed by a pair of broad fleshy lips armed with rows of tiny horny teeth—a curious place for teeth; the mouth itself is furnished with a pair of teeth—also horny—resembling the beak of a parrot.

During this time these tiny little creatures bear a really close resemblance to the young of many fish. In both young fishes and tadpoles, for some time after leaving the egg, breathing is done by means of very delicate branching gills, standing out on each side of the head. One of these branches, highly magnified, is shown in fig. 3; at C (fig. 1) the gills are shown in their natural position. If you can manage to place a tadpole at this stage under the microscope, you will see the blood, in the shape of little oval discs, coursing through the blood-vessels of these gills. These breathing organs, however, are a source of danger, for they are easily injured, so that, in the tadpole, as in the fish, they are soon replaced by gills enclosed within a little chamber on each side of the head. Breathing now takes place by drawing water in at the mouth, passing it through the chambers and over the gills, and expelling it through a small hole which opens in the form of a short tube on the left side of the neck (shown in fig. 4), if a neck can be distinguished in an animal where the head passes insensibly into the body! But yet another change in the breathing apparatus takes place. During the time that the gills are being changed, a pair of lungs are being developed, and the first hint that they are growing is given by the frequent journeys to the top of the water for the purpose of sucking in air.

(Concluded on page 37.)